Positioning a can on a rotating turret

ABSTRACT

In a high speed apparatus having a rotating turntable, an infeed device has a rotatable turret from which radiate a plurality of can holders which act to transfer cans from an infeed conveyor along an encircling guide rail to the rotating table. A cam element enclosed in the turret may cyclically retract each holder to cause the can to follow the periphery of the rotating turntable.

TECHNICAL FIELD

This invention relates to a transfer apparatus for positioning a can ina desired position on a rotating table or turret so as to permit theinsertion of a closely fitting mandrel into the can as the tablecontinues its rotation.

BACKGROUND ART

In the can handling art it is frequently necessary to remove individualcans one at a time from a conveyor delivering a row of like cans, and toplace each can at a precise location in the periphery of a rotatingturret. In known machines used to seam a can end to a can body, a longscrew is used to receive each can in its screw thread, and by virtue ofthe screw thread profile to present each can to a recess in theperiphery of a rotating star wheel. The star wheel is rotated so thateach can in turn is presented to a work station at the rotating turret.

A geometrical limitation of such an arrangement arises from thenecessity for the arc of rotation of the star wheel to coincide with thearc of rotation of the turret, so as to allow a can to be safely andstably deposited from the rotating star wheel on to the rotating turret.Such a coincidence is at best an instantaneous coincidence of twotouching arcs, or at worst an overlapping mismatch of two intersectingarcs. Neither such an instantaneous coincidence, nor such a mismatching,of the two arcs permits the satisfactory insertion of a closely fittingmandrel into a can as it is delivered by the star wheel on to the turretas both continue their respective rotations.

The present invention seeks to provide a transfer arrangement fordelivering cans from a rotating star wheel to a rotating turret in sucha way that a closely fitting mandrel can be safely inserted, at leastpartly, into a can during its transfer from the rotating star wheel tothe rotating turret.

U.S. Pat. No. 4,059,186 (Aschberger) has a similar objective, andprovides in an infeed transfer apparatus for transferring articles to arotating table for cooperation there with successive,circumferentially-spaced article treatment means carried on said table:

(a) a turret member mounted for rotation about a fixed axis parallelwith an axis of rotation of the rotating table;

(b) a plurality of article holders extending radially from the turretmember at positions spaced around the periphery thereof and arranged formovement toward and away from said fixed axis;

(c) holder operating means comprising (i) a stationary annular camdisposed concentrically about said fixed axis, and (ii) for each suchholder, a cam follower coupled to the holder, and a spring biasing meansadapted to bias the holder into contact with said cam; and

(d) an article guide rail extending around a part of said turret memberand spaced radially therefrom, said guide rail having a first arcuatepart which is concentric with the turret, and a second arcuate partwhich is continuous with said first part and which is concentric withsaid rotating table.

DISCLOSURE OF THE INVENTION

According to the present invention such a transfer apparatus ischaracterised in that:

(i) said turret member comprises a transverse wall, and an annular sidewall extending from the periphery of said transverse wall;

(ii) said cam is disposed radially within said side wall;

(iii) a plurality of circumferentially-spaced radial shafts are slidablymounted in said side wall for reciprocatory sliding movement toward andaway from said guide rail, each said radial shaft carrying outside saidside wall one said article holder and inside said side wall one said camfollower; and

(iv) said spring biasing means are carried within said side wall and arearranged to urge the respective cam followers radially outwards againstsaid cam.

In one preferred arrangement, a turret driving shaft is coupled to anddepends centrally from said transverse wall, and said side wall dependsfrom the periphery of said transverse wall.

Preferably, the apparatus also includes a stationary transverse wallhaving a central aperture through which said driving shaft extends,which wall is adapted to enclose and protect said cam, cam followers andbiasing spring means from a damaging external wet environment.

Inner and outer annular side walls may be upstanding from inner andouter peripheries of said stationary transverse wall thereby to form areservoir for receiving a lubricating oil, and distributor means may beadapted to distribute such oil from said reservoir to moving partsdisposed within a space enclosed by the respective moving and stationarytransverse and annular side walls.

The distributor means may include a cylindrical, oil pumping sleevefitting closely around said stationary, inner annular side wall anddrivingly coupled for movement with the moving transverse wall of theturret, which sleeve has formed in its inner surface a spiral pumpinggroove.

Preferably, each said radial shaft is slidably mounted in a withdrawablebearing unit, which bearing unit is demountably carried in said turretside wall in a manner such as to permit it and its associated radialshaft and cam follower to be withdrawn as a single operating unitradially outwards from said side wall.

Each said withdrawable bearing unit may also incorporate the associatedspring biasing means.

In a preferred embodiment, said annular cam is disposed below saidradial shafts; each such radial shaft carries a dependent stub shaft;and each said stub shaft carries a rotatable roller which constitutesthe associated cam follower.

Other features of the present invention will appear from a reading ofthe description that follows hereafter and of the claims appended at theend of that description.

One transfer apparatus according to the present invention, asincorporated in an electro-coating apparatus, and its method ofoperation, and various modifications of such transfer apparatus, willnow be described by way of example and with reference to theaccompanying diagrammatic drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In those drawings:-FIG. 1 shows a pictorial representation of theelectro-coating apparatus and the associated infeed transfer apparatusfor feeding cans which are to be electro-coated; FIG. 2 showsdiagrammatically an enlargement of a lower part of the FIG. 1; FIG. 3shows a plan view of the infeed device; and FIG. 4 shows in a verticalcross section the construction and mode of operation of the infeeddevice, which cross section is taken on a diametral plane of the infeeddevice.

BEST MODES OF CARRYING OUT THE INVENTION

In the description that follows hereafter, an asterisk shown inassociation with a reference number indicates a first mention of thatreference number.

Referring now to the drawings, FIG. 1 shows an electro-coating apparatusfor electro-coating metal can bodies 128* (referred to hereafter simplyas `cans`) of the kind having a cylindrical side wall extendingintegrally from a base wall. For a full description of the apparatus,the reader's attention is hereby directed to the co-pending U.S. patentapplications which are listed at the end of this description.

Briefly, however, the electro-coating apparatus comprises a turntable14* having mounted in an upper plate 16* thereof a series of spacedelectro-coating cell bodies 96* into which respective upright cans 128are to be introduced from below, and then be enclosed by, respectivepneumatically operated cell closers 100*, for the performance of theelectro-coating process. Each electro-coating cell body 96 incorporatesa system of concentric electrodes between which the side wall of the canis to be accurately and concentrically positioned for electro-coating.

Cans 128, delivered spaced apart by a screw conveyor 338*, aretransferred to the electro-coating apparatus by an infeed transferdevice 326*. That device comprises a rotary turret 334* from which aseries of spaced can holders or pockets 336* radiate. Those holders arearranged to drive the respective cans along a circular locus in contactwith a first arcuate part of a fixed guide rail 340* of the infeeddevice, and to deliver the respective cans in turn to the respectivecell closers 100, at a predetermined infeed station, as they continue atconstant speed along their circular locus 350 with continuing rotationof the turntable 14.

In order to ensure a stable deposit of each can 128 on its respectivecell closer 100, the guide rail 340 has a second arcuate part 351conforming to the locus 350 of the moving cell bodies 96 on theturntable. The can holders 336 acting in cooperation with this secondpart of the guide rail are arranged to bring each can in turn into thecircular locus 350 of the associated moving cell body 96, and then tomove the can along that circular locus 350 whilst the cell closer 100 isbrought up from below into contact with the can 128.

Each can holder 336 thereafter returns to its normal circular locus inreadiness for receiving its next can from the screw conveyor 338.

As shown in the FIG. 4, each can holder 336 is carried within the turret334 on a retractable shaft 342* which is biased by an helicalcompression spring 344* to an outer can-guiding position. That shafthas, within the turret, a cam follower wheel 346* which is urged by theaction of that biasing spring radially outwards against the shapedinternal surface of a static, generally circular cam 348*. That camsurface is shaped so as when the can holder moves into the position fordepositing a can 128 on the cell closer 100 then at the infeed station,it is gradually and temporarily retracted slightly so as to enable thecan holder to follow for a short way the locus 350 of the cell closer100 as it moves into, through and beyond the infeed station. Thisenables the can to be properly transferred to and positioned on the cellcloser, since the can holder and cell closer move for a short way alongthe same locus. The guide rail 340 is shaped as shown at 351 so as tocause the can to move into and along that locus 350.

In more detail, the infeed turret 334 comprises an inverted cup-shapedmember 500* secured at the top of a driving shaft 502* which rises,through a tubular shroud 504*, from a torque-limiting device (not shown)which is connected to the gear wheel 330*. That shroud passes upwardlythrough a transverse support channel 506* which carries on its uppersurface a fixed, turret-location socket 508*. Secured in that socket isa turret support means 510* which incorporates a lubricating oilreservoir tank 512*. An upstanding tubular member 514* constituting aninner wall of that oil tank encloses the driving shaft 502 which extendstherethrough with clearance. A seal 516* provided at the upper end ofthat tubular member 514 prevents the exit of lubricating oil betweenthat member and the driving shaft.

The turret incorporates a dependent, inner cylindrical wall 518* ofwhich the lower end is rotatably supported on a ball bearing race 520*which is itself carried on a transverse platform 522*. That platform issecured by screws on an upstanding intermediate cylindrical wall 524*which rises out of the oil tank and which has in its lower part anaperture 526* to allow circulation of the lubricating oil within thetank.

An oil pumping sleeve 528* encircles the upstanding tubular member 514,is secured at its upper end in the inner dependent wall 518 of theturret, and has formed in its bore a spiral, oil-pumping groove 530*.Thus, on rotation of the turret, oil from the reservoir rises up thespiral groove and is delivered at the upper end of the sleeve 528 into aplurality of radial, distribution ducts 532* from where it escapes viavertical nozzles 534* into the spaces enclosed below.

The lower rim of the outer cylindrical wall 536* of the turret has anannular groove 538* into which extends the thin upper rim of the outercylindrical wall 540* of the oil reservoir tank 512, in such manner asto prevent the ingress of electro-coating fluid into the reservoir tank.The lubricating oil surface level indicated at 542* is maintained at aheight such as to prevent the loss of oil between the tongue-and-groovejunction of the outer walls of the turret and oil tank.

The turret has secured around its circumference at each of eightequi-spaced positions a respective can holder unit 544*, which isremovably carried within radially-aligned, large and small apertures546*, 548* formed respectively in the outer and inner cylindrical walls536 and 518 of the turret.

Each can holder unit comprises a slotted body 550* which is provided atone end with a fixing flange 552* and an adjacent spigot portion 554*for locating and securing (by screws not shown) the unit in position inthe aperture 546, and at the other end with a plug portion 556* whichlocates in said smaller aperture 548.

The retractable shaft 342 supports at its outer end the associated canholder 336, is slidably carried in respective radially-aligned bores558*, 560* formed in the respective end portions of the slotted body550, and has a central waisted portion 562* in which is carried avertical stub shaft 564*. That stub shaft is secured in position by anut 566* which engages the slotted body via a slide block 567* carriedin a slide way formed in the slotted body, and carries rotatably mountedat its lower end the said cam follower wheel 346. The biasing spring 344is trapped on the retractable shaft 342 between shoulders formed on thatshaft and in the slotted body.

The transverse platform 522 has at its outer periphery an upstandingwall 568*, of which the inwardly facing surface constitutes the saidcircular cam 348.

Sealing rings 570* are provided on the retractable shaft, and behind thefixing flange 552, to prevent the ingress of electro-coating fluid intothe turret, and also to prevent the egress of lubrication oil. Annularshrouds in the form of flexible bellows 572* are provided on theretractable shaft 342 and the fixing flange 552, and a tubular extension574* is provided on that flange, all for that same purpose.

The reader's attention is hereby directed to the followingconcurrently-filed, co-pending U.S. patent applications which claimother aspects of the electro-coating apparatus referred to above:namely--Ser. Nos. 07/193,452; 07/193,454; and 07/193,455, all filed May6, 1988.

What is claimed is:
 1. Transfer apparatus for transferring articles to arotating table for cooperation there with successive,circumferentially-spaced article treatment means carried on said tablecomprising:(a) a turret member mounted for rotation about a fixed axisparallel with an axis of rotation of the rotating table; (b) a pluralityof article holders extending radially from the turret member atpositions spaced around the periphery thereof and arranged for movementtoward and away from said fixed axis; (c) holder operating meansincluding a stationary annular cam disposed generally concentricallyabout said fixed axis, and for each such holder, a cam follower coupledto the holder and spring biasing means adapted to bias each holder intocontact with said stationary cam; (d) an article guide rail extendingaround a part of said turret member and spaced radially therefrom, saidguide rail having a first arcuate part which is generally concentricwith the turret, and a second arcuate part which is continuous with saidfirst part and which is generally concentric with said rotating table;characterized in that:(i) said turret member comprises a transversewall, and an annular side wall extending from the periphery of saidtransverse wall; (ii) said cam is disposed radially within said sidewall; (iii) a plurality of circumferentially-spaced radial shafts areslidably mounted in said side wall for reciprocatory sliding movementtoward and away from said guide rail, each said radial shaft carryingoutside said side wall one said article holder and inside said side wallone said cam follower; and (iv) said spring biasing means are carriedwithin said side wall and are arranged to urge the respective camfollowers radially outwards against said cam.
 2. Transfer apparatusaccording to claim 1, wherein a turret driving shaft is coupled to anddepends centrally from said transverse wall, and said side wall dependsfrom the periphery of said transverse wall.
 3. Transfer apparatusaccording to claim 2, including a stationary transverse wall having acentral aperture through which said driving shaft extends, which wall isadapted to enclose and protect said cam, cam followers and biasingspring means from a damaging external wet environment.
 4. Transferapparatus according to claim 3, including inner and outer annular sidewalls upstanding from inner and outer peripheries of said stationarytransverse wall thereby to form a reservoir for receiving a lubricatingoil, and distributor means adapted to distribute such oil from saidreservoir to moving parts disposed within a space enclosed by therespective moving and stationary transverse and annular side walls. 5.Transfer apparatus according to claim 4, wherein said distributor meansincludes a cylindrical, oil pumping sleeve fitting closely around saidstationary, inner annular side wall and drivingly coupled for movementwith the moving transverse wall of the turret, which sleeve has formedin its inner surface a spiral pumping groove.
 6. Transfer apparatusaccording to claim 1, wherein each said radial shaft is slidably mountedin a withdrawable bearing unit, which bearing unit is demountablycarried in said turret side wall in a manner such as to permit it andits associated radial shaft and cam follower to be withdrawn as a singleoperating unit radially outwards from said side wall.
 7. Transferapparatus according to claim 6, wherein each said withdrawable bearingunit incorporates the associated spring biased means.
 8. Transferapparatus according to claim 6, wherein said annular cam is disposedbelow said radial shafts; each such radial shaft carries a dependentstub shaft; and each said stub shaft carries a rotatable roller whichconstitutes the associated cam follower.
 9. Transfer apparatus accordingto claim 7, wherein said annular cam is disposed below said radialshafts; each such rotatable shaft carries a dependent stub shaft; andeach said stub shaft carries a rotatable roller which constitutes theassociated cam follower.